Highly Stable Protonic Ceramic Electrolysis Cells Based on Air Electrodes with Finger-Like Pores Current Collection Layers Running in High-Steam-Content Air.

Abstract

The steam content in the air electrode is one of the major factors determining the efficiency and stability of protonic ceramic electrolysis cells (PCECs). In this work, the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) current collection layer (CCL) film with unique finger-like pores was successfully prepared by the phase-inversion tape-casting technique (PT), which promoted the gas diffusion inside the electrode and effectively improved the stability of the single cell in high-humidity air. A screen-printed LSCF-BaCe0.7Zr0.1Y0.1Yb0.1O3 catalytic active layer (CAL) was also applied to match the thermal expansion coefficient (TEC) values and improve the interface combination. The electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) studies of the symmetric cells showed that when the film was used to match different CALs as an air electrode, the gas diffusion inside the electrode was no longer restricted by the increasing steam content in air. The single cell exhibited a high electrolysis current density of 1 A cm-2 (1.25 V) at 650 °C; furthermore, no performance degradation was observed in this high current density when electrolyzed in air with 40 and 60% humidity for more than 250 h. These results present a simplified and economical scheme to develop air electrodes with high stability in wet air with a high steam content.